...is “wacky” old man bragging that he WAS withholding money unless a prosecutor was fired should be a problem!
That is a nutty conspiracy theory. 1. It was already US policy to withhold the aid. 2. The aid was being withheld because the IMF, and the US thought that the then Ukraine prosecutor was too weak on corruption.
But even suppose you are 100% right, it makes no difference as to whether or not Trump committed high crimes. If you get charged with drunk driving do you show up in court and say my neighbor drove drunk two weeks ago and nobody stopped him, therefore, I am innocent? No, of course, you don't. What your neighbor did two weeks ago has nothing to do with what you did. You are making the same illogical argument that somehow Trump is innocent because you believe Joe Biden did something wrong.
Trump already tried to get the US government to investigate the Bidens. Government officials, experts in his own Administration and even Bill Barr said there was nothing there. That it was a "debunked conspiracy theory." Trump's unwavering belief in a cable news conspiracy theory and a desire to rig the 2020 election drove him to commit crimes. Accept that he is a crook and move on.